Urinary incontinence, vesicourethral reflux, fecal incontinence, intrinsic sphincter deficiency (ISD) and gastro-esophageal reflux disease, are examples of disorders, among others, that have responded to treatments with augmentative materials. In addition, it is known to use augmentative materials for aesthetic improvement, including improvement of skin contour.
For instance, a common method for treating patients with urinary incontinence is via periurethral injection of a bulking material. One such bulking composition is a paste known commercially as POLYTEF or URETHRIN. This paste is comprised of a fifty-fifty (50-50) by weight mixture of a glycerin liquid with polytetrafluoroethylene (PTFE) particles and is sold by DuPont. Over a period of time, the glycerin dissipates into the body and is then metabolized or eliminated, reducing the effective volume of the bulking material. Consequently, to achieve the desired result, the surgeon can overcompensate for the anticipated loss of bulking material by injecting a significantly larger amount of material than is initially required. However, the eventual dissipation of the glycerin complicates the surgeon's ability to gauge the appropriate amount of bulking material to inject. Furthermore, in extreme circumstances, such overcompensation can lead to complete closure of the urethra, which could put the patient into temporary urinary retention. As a result, the surgeon may ultimately not inject enough bulking mixture into the patient, leading to the need for a second or even a third procedure to inject additional material.
An alternative to PTFE paste is a collagen gel such as CONTIGEN, available from C R Bard. The collagen gel is injected and forms a fibrous mass of tissue around the augmentation site. This fibrous mass, created by the collagen injection, however, also dissipates over time and is eventually eliminated by the patient's body. As a result, additional injections are periodically required.
Yet another alternative is a hard particle suspension. One such commercially available product is DURASPHERE available from Carbon Medical Technologies. These hard particles, carbon coated zirconium beads, are injected in a beta-glucan carrier. The beta-glucan is eliminated by the patient's body over time. Moreover, in many cases, migration of the particles after administration appears to reduce the bulking effect of the particles over time. As a result, additional injections may be required.
In this regard, methods of injecting bulking agents commonly require the placement of a needle at a treatment region, for example, peri-urethrally or transperineally. The bulking agent is injected into a plurality of locations, assisted by visual aids, causing the urethral lining to coapt. In cases where additional applications of bulking agent are required, the newly added bulking agent may need to be injected at a higher pressure than the pressure at which the initial bulking agent was injected.
From the above, it is apparent that there is a need for bulking compositions which do not require supplemental injections or which require less frequent supplemental injections.